Recent advances in the study of the regulation of cell death by apoptosis s
uggest that changes in mitochondrial permeability frequently precede the de
velopment of morphological features such as chromatin condensation, phospha
tidylserine inversion of the outer cell membrane and the activation of endo
nucleases. There is evidence that this permeability transition is associate
d with, and may be regulated by, changes in the intracellular redox potenti
al. The role of the tripeptide thiol glutathione in the regulation of apopt
osis-associated redox changes and the control of mitochondrial membrane per
meability is reviewed in this article.